Method and apparatus for cleaning asbestos



F eb. 8, 1949.

Filed Aug. 5, 1944 METHOD AND-APPARATUS FOR CLEANING ASBESTOS 2Sheets-Sheet 1 BY/U- of" ATTORNEY Feb. 8, 1949. F, J, KOEHNE 2,460,938

METHOD AND APPARATUS FOR CLEANING ASBESTOS Filed Aug. 5, 1944 y Tula.

www@ Ich ATTORNEY and is particularly Patented Feb. 8, 1949l METHOD ANDAPPARATUS FOR CLEANING ASBESTOS Frank J. Koehne, Martinsville, N. J.,assignor to Johns-Manville Corporation, New York, N.v Y., a corporationof New York Application August 5, 1944, Serial No. 548,295

16 Claims. l

This invention relates to the opening and cleaning of asbestos andsimilar iibrous materials, concerned with improvements in method andapparatus whereby asbestos may be simultaneously opened and cleaned tosegregate the fibers and fine and coarse impurities including dust androck particles adhering thereto Crude and partially opened asbestosfibers such y as are presently available for industrial purposes consistof rodlike bundles of. desirable iine asbestos bers or laments withwhich are associated substantial amounts of undesirable impuritiesincluding asbestos iines, rock gangue and dust. Conventional methods oftreating such unclean asbestos fibers, as by milling, windowing andscreening to separate impurities therefrom, vdevelop serious attritionand breakage of the fibers, thus producing a librous product which has amarket value substantially lower than the potential market value oi theunbroken i'lbers.'

Dilculties are to be expected in attempts to apply conventionalpneumatic impact pulverizing and cyclone separating and classifyingmethods and equipment designed for handlingl granular products, to theproblem of cleaning crude and unclean asbestos. signed for cycloneclassification of granular products are predi-cated on Stokes Law, whichapplies specifically to granular particles but not to. brous materialssuch as asbestos. The separation of granular particles according toStokes Law is effected according to particle size, or more accurately inaccordance with-the average diameters and masses of the particles. temptto adapt cyclone separating and ing equipment designed for handlingmaterials, to the treatment of brous classifygranular material such asasbestos, would necessitate maintenance of suitable turbulence in thepneumatic system in order to cause the fibers to behave as sphericalparticles such as the equipment is designed to handle. In the absence oiturbulence, the fibers tend to orient themselves into alignment with thelongitudinal axis of the cyclone separator and to discharge rapidlyunder gravity pull from the classication zone. When librous materialsare subjected to suilicient turbulence to cause Methods and equipmentde- Any atthem to behave as spherical masses in a pneumatic vortexcleaning system, any cleaning effect which may result from suchtreatment is at least partially cancelled by the tendency of the openedfibers to attract back to their enormously greater exposed arca surfacesimpurity nes and dust initially liberated during impact pulverizing 2treatment. Accordingly, the more thoroughly the brous bundles areberized or opened by the initial impact pulverizing treatment, and thegreater the resultant ratio of length to thickness of the iibers, theless easily can the opened bers be cleansed of iine non-librous impurityparticles or dust by conventional cyclone cleaning and classifyingequipment.

A primary object of the invention is to provide method and apparatus ofimproved characteristics adapted to eiliciently and economically openand clean crude and unclean asbestos bersl.

A more particular object is that of providing improved method andapparatus whereby crude and unclean asbestos bers may be simultaneouslyopened and separated from coarse and iine impurities including rockparticles and dust adhering thereto, while avoiding serious degradationof the fibers.

According to the present invention, asbestos bers undergoing treatmentmust be thinly suspended in an air stream of suflicient volume to acceptand carry away impurity dust particles as they are'separated from theber filaments. The crude or unclean asbestos bers are introduced intothe upper portion of an upright generally cylindrical opening andcleaning chamber, and the fibers drop gradually by gravity pull throughan upwardly rising vortex of cleaning gas or air. Means such as rotatingpaddle or fan blade assemblies are provided for establishtions of thevortex. Centrifugal force actinguniformly on the libers, tends to'suspend them and hold them adjacent the periphery ofthe vortex andadjacent the walls of the cleaning zone. By maintaining a high ratio ofrotational movement in relation to gravitational downward movement, thebers are caused to travel in a. path of such length as. to comb theminto longitudinal alignment with the rotational direction of theirmovement. Means such as reentrant fins are provided at intervals alongthe inside walls of the cleaning zone, which act to intermittently orperiodically deilect the rotating body of suspended fibers andsuspending Igas or air inwardly away from the walls of the cleaningzone. The bers resist the intermittent deilection impulses therebycreated by virtue of their greater momentum. The bers are thereby ilexedand bent by the more compressible and deflection responsive airimpulses, as successive portions of each liber lament length aresubjected to these pulsating lateral impulses. The resulting exing andbending opens the fibers and chips off attached impurity particles,Movement of the suspending air or gas transversely back and forth acrossthe fiber filaments scours the filaments of adhering dust and rockparticles. while avoiding serious attrition of the fibers orrecontamination thereof by the separated dust. This opening and cleaningoperation is followed by final classification segregation of cleanfibers from liberated granular and dust particles by'selective action ofcentrifugal, gravitational and rising gas vortex suspension forces.

With the aforementioned objects and features in view, the inventionconsists in the improvements in method and apparatus for cleaning andberizing asbestos and similar fibrous materials which areherelnafterdescribed and more particularly defined by the accompanying claims.

In the following more complete description of the invention, referencewill be made to the attached drawings, in which:

Fig. l is a diagrammatic assembly'view, with parts shown in verticalsection. of a preferred' arrangement of apparatus adapted for thepractice of the invention;

Fig. 2 is a horizontal section of one of the fiber cleaning chambers,taken on the line 2-2 of Fig. l;

Fig, 3 is a horizontal section through a segment of an invertedtruste-conical lining of one of the cleaning chambers. taken on the line3--3 of Fis. 1;

Fig. 4 is a horizontal section through a segment of the invertedfrusta-conical lining in the upper portion of the last cleaning chamberof a series, taken on the line l-A of Fig. l; and

Fig. 5 is a horizontal section through a segment of the invertedfrusta-conical lining in the lower section of the last cleaning unit ofthe assembly shown in Fig. l, taken on the line S-S of Fig'. .1.

The improvements in method and apparatus of the present invention aredesigned to effect the berizing and cleaning of fibers while thinly sus`pended in air, and to develop enicient separation f and segregation ofcleaned fibers and fine and coarse non-fibrous contaminants in the sameoperation in which the fibers are flberized and liberated from suchcontaminants.

A preferred apparatus assembly for the practice of the invention isportrayed in Fig. l. This 'apparatus may include a shaker screen I0 fromis effected through a tangential offtake 34 from which this air iscarried to a cyclone fiber separator 36. Central air exit ports of eachof the cyclone air separators 32 and 3G may be connected to the inlet ofa common suction fan 38. The discharge nozzle of fan 38 is shown asconnected to the tangential inlet of a cyclone dust separator 40.

Inverted frusta-conical inner lining members 42 have been shown asmounted in the lower portion of each cleaning chamber I6, I8 and 20. Theupper top rim of each lining member 42 is dimensioned for mounting toform a tight sealing fit with the inner cylindrical wall of the chamber.A similar inverted frusto-conical inner lining Mi is shown as mountedadjacent the top of clean- A ing chamber 20. Reentrant fins 46 andadjacent cated tangentially near its base.

slots I8 are shown las located at spaced intervals around the liningmembers 42 and M in relative arrangements and for purposes which arehereinafter more fully explained. Each of chambers I6 and I8 has acleaned fiber exit port 50 lo- Chambers I5 and I8 also have coarseimpurity exit ports which coincide with the axial air intake ports 2E.

Chamber 20 has a gas pervious frusto-conical base 52 and an impuritygranule exit port 54 at the base circumference.

In operation, an air or gas suspension of unclean asbestos fibers ispicked up by suction from shaker screen feeder Iii (Fig. l). Vibratingor shaker screen feed tables of the type shown are advantageouslyemployed for initially cleaning mixtures of short asbestos fibers androck gangue. Fiber containing excessive rock content may beadvantageously fed over a shaker or vibrating screen having an air inletI I directed through its screen bottom through which air may be forcedupwardly for the purpose of elevating and maintaining the bers in ablanket above the rock on the screen to give the suctiony hood i2 everyopportunity to remove such fibers as were formerly weighted down by rockduring the brief interval of their passage under the suction hood.Longer grades of asbestos fibers may be supplied to the cleaningchambers of the present equipment by a picker-belt feed mechanism.

Crude or unclean fiber is delivered through inlet ports I5 into the topportion of each of the cylindrical cleaning chambers I6, I8 and 20. The

` paddle or fan assemblies 2-4 operate to suck a the top of which fibersto be cleaned are picked up by a suction hood I 2 and transported in airsuspension through a suction fan I'l. From fan i4 the air suspendedfibers are discharged into the upper peripheral section of the first ofa series of upright cylindrical ber opening and cleaning chambers ordrums IB, I8 and 2U. Motor driven vertical shafts 22 are mounted axiallyin each of the cleaning chambers I8, I8 and 2li, each shaft beingsupported by top and bottom bearings. Two vertically spaced sets of fanblades or paddles 24 are shown as rotatably mounted on each shaft 22 inposition to develop suction intake of cleaning air or gas through anintake port 2 at the base of each chamber, ansi to promote rotation ofthe air within each cleaning chamber in an upwardly rising air vortex.Air thus introduced into cleaning chambers I6 and I8 finally escapestherefrom through axial top oitakes 28, from which it is conducted bypipes 30 to cyclone dust separators 32. Escape of air which isintroduced into cleaning unit 20 large volume of cleaning air into eachchamber through the bottom air intakes, and to generate in each of thechambers an upwardly7 rising air vortex which picks up the uncleanfibers and retards the rate at which they settle through the chamberunder gravity pull, while transporting the fibers in suspension andunder the inuence of centrifugal force in a long path around the innerperiphery of eachcleaning chamber. By thus forcing the bers to travel ina circular path around the inner lining of the cleaning chamber, theirpath of travel is so extended as to afford ample time for theorientation of the fibers with their major axes aligned with thedirection of rotational travel. This centrifugal force tends to pin thebers to the outside walls of the cleaning chambers.

Fins 45 which are attached at spaced intervals to the inside surfaces ofthe chamber lining, serve to periodically deflect the rapidlycirculating air and ber stream toward the laxia1 center of the cleaningchamber in a. direction opposed to the direction normally imposed bycentrifugal torce. Since the. entraining air is compressible,;centrifugal force. intermittently op posed by the` deflecting actionofthenns 4I. develops a fluctuating pumping action forcing Vthe airtransversely in and out across the path of the moving fibers, vwhereasthe greater momentum of the fibers tends to keep them travelling in acircular path and to resist such deflection. The result of suchpulsating of the compressible air carrier is to cause bending 'andflexing of the fibers, as successive portions of their lengthenter andleave the areas wherein this lateral pulsation is induced. The flexingand bending of the individual fibers or fiber bundles tends toopen andsplit the fibersand to chip loose from their surfaces any adhering dustand granular impurities. o celeration between the fibers and theentraining air develop a scouring action upon the flexing fibers, whichstili further aidsseparation oi' non fibrous impurities from the fibers.The clean air which is brought in from the bottom gradually works itsway upward through the cleaning chambers as a vortex from which the airfinally exits at ports 28 carrying with it an entrapped load of fineimpurity dust liberated from the fibers.

Variations in rate of movement or ac- Fins 48 may be attached directlyto the vertical cylindrical walls of the cleaning chambers I6 and I8.However, it is deemed advantageous to erect such fins in the form of aninverted frusto'- conical cone 42 having its upper and larger rimdimensioned to the inner circumferential dimensions of the cleaningchamber and rigidly attached thereto. With this inverted frusto-conicalarrangement of the reentrant fins as an inner lining for the cleaningchamber, part of the air which is introduced to the base of the chambermay be circulated around the outside of the fin lining and finallyintroduced to the cleaning chamber through slots 48 disposed immediatelybehind the reentrant fins, in the manner particularly shown by Fig. 3.With this modification, an inrush of additional cleaning air takes placethrough slots. immediately adjacent and behind each reentrant fin in thepath ofthe air and fiber which is circulating within the heatingchamber. As the iibersand suspending air travel across and adjacent eachfin, a pressure drop takes place in the eddy current immediately behindthe fin, and this pressure drop develops inrush of additional cleaningair through a slot 48. After the air and suspended fiber has passed thefin 46 and the slot 48, unopposed centrifugall force operates to againdrift the air suspended fiber toward the circumference. of the chamberthrough the additional body of cleaning air thus suppliedby slot 48.

The general movement of cleaning air through the chambers I8 and i8 isupward and then inward. As the fibers gradually descend through thisrising vortex oi.' air, the air operates to pick up fine dust and nesliberated by the fibers and to carry ofi' suchfines in suspensionthrough. the air exit. Introductionvof cleaning air through slots 48tends to displace dust laden air inwardly toward the exit 28 of thecleaning chamber. while the outer layers of air suspended fibers aresubjected to bathing and scouring by added cleaning air.

The-cleaning chambers are designed to operate gently on crude, unopenedfiber bundles to fiberize such bundles by flexing and by mild impactagainst the reentrant fins and chamber linings, While cushioning thefibers against serious disintegration. Any crude unopened fiber untiltheir. classification and physical characteristics meet acceptablespecifications.

Suitable dimensions for the cylindrical cleaning chambers I6, I8 and 20include lengths of about 4% ft. and internal diameters approximating 3ft. The fans which develop and maintain a rising vortex of airthroughout the chambers may be four bladed fansof approximately 2 inchblade width located in sets mounted respectively at elevations ofapproximately six inches and 36 inches above the bases of the cleaningchambers. Buch fans lare rotated at speeds which are adjustable maintainair velocities in the range 30D-1500 ft. per second at the periphery ofthe upwardly rising air vortex. Peripheral air speeds lower than 300 ft.per-second are unsatisfactory because the Dull of gravityallows thefibers to settle out of the cleaning unit at a rate too fast to permitsuitably eiilcient flberizing and cleaning action. Air velocity ratessubstantially greater than 1500 ft. per second tend to develop excessiveilberizing and breakdown of opened fibers, causing undesirableshortening of open fiber length. The apparatus shown in Fig. 1 isdesigned tc effect substantially complete separation of fine sagethrough chambers i8 and I 8. and to utilize chamber 20 for effectingfinal separation of clean opened fibers from coarse rock and unopenedcrude fibers. by settling out such coarse impurities. The invertedfrusto-conical lining 44 which is mounted in the upper portion ofchamber 20 is designed to act as a removal trap or gate for' the cleanand opened' fibers. The fiber with its entrainingy air is fed into thetop of chamber 20, and as it settles it is moved by centrifugal force bythe upwardly rising air vortex toward the periphery walls of thechamber. As the fibers travel in a rotational path adjacent the innerface of cone 44, they pass over defiecting iin elements 48 (Fig. 4),behind which fins lie slots 48 which form the only means of egress forthe air and opened fibers leaving the cylinder 20. Fibers which havebeen sufficiently cleaned and opened l can be made to reverse theirdirection of travel and to emerge through the slots 48 in cone 44,

while heavier and coarser incompletely opened crude flbersand'coarsegranular impurities are carried by their greater momentum past the slots44 and are thereby retained within the chamber while settling undergravity'pull into the lower portion of chamber 2li. i

The arrangement of defiectingfins 46 and slots 48 in cone 42 at the baseof chamber 20 may be such as portrayed in Fig, 5. In this casethereentrant iins are turned inwardly in a direction opposed -to thedirection ofrotation of the air' within the chamber, with the forward orscalping edges 5I of such fins presented as traps for heavy particlescarried by the rotating air in closely4 abutting relation to the innerwall of cone 42.' Centrifugal force rotates the entrained rock andthrough the treating-chamcrudy fibers directly toward theforward'scalping I8, and such particles are trapped and electedoutwardly by the scalping edge and n through the slot louvers forwardlyof the: iin elements, and

settle by gravity to the base of the chamber il, where they aredischarged through the outlets I4.

Any sulciently opened bers which are present J:Medocal prolonged andrepeated exing.' bending and scouring treatment of the bers whilesupporting them in ges suspension, as the principal ber opening'andcleaning inuence. A substantial s ber opening and cleaning effect isdeveloped by the turbulence obtained at points adiacent the rewentrantdns, asa result of impingement and-collision of impurity particles andbers. Important factors in the summation of mechanical disinlo tegrationas the chief fiberlzing inuence consist in the air stream flowing pastthe inner lining of the bottom. cone 42 in chamber 20 are deflected awayfrom the scalping `edges of the ns Il by the blasts of air enteringthrough ports 48. and such kfibers are carried forwardly out of thelower section of the chamber by the rising air vortex and finally exitfrom the chamber through the exit ports in cone Il.

The principal ber opening and cleaning sections of the illustratedapparatus lie in the zones of chambers i8 and i8 which are confinedradially -by the inverted frusto-conicai defiector fin linings. Thatportion of each of chambers il and Il which underlies the restrictedneck at the base of the inverted cone forms a radially extendedclasslcation zone in which the opened or partially opened bers arethrown outwardly by the rotation of the revolving fan blades 2l, to beremoved tangentially from the base of the apparatus. while heavyimpurities of more nearly spherical shape are discharged from the bottomof the inverted cone toward the centrally located air inlet port, in azone where the centrifugal forces are insufficient to throw suchgranular particles toward the periphery. In other words, the finalsegregation of the opened and cleaned bers from the heavier or coarserimpurities. takes place in the lower portion of the cleaning chambersbelow the point at which a powerful vortex is developed. In the upperportions of the chambers I6 and I8 the operation which takes place isprimarily that of segregation and classification of crude or partiallyopened asbestos and of light dust or fine impurities. The light dustparticle impurities are carried off by entrainment in the inwardlymoving air stream which exits from the axial top center of the chambers,whereas the heavier crude and partially unopened bers are forced towardthe outer periphery of the vortex by centrifugal action.

The method and apparatus which is herein described is particularlydirected to the purpose of effecting opening and cleaning of crudeasbestos without serious disintegration or attrition of opened andcleaned fibers. To accomplish this purpose, the individual nberizing andcleaning chambers of the apparatus are preferably limited in size to a,comparatively low unit treating capacity, and several of such units arepreferably operated in series, in order that the partial ber opening andcleaning operation which takes place in 'one unit may be carried forwandto completion in a succeeding unit. In traversing one of the flberlzingand cleaning units I6 or I8 from its top liber inlet to its bottomtangential liber outlet, the crude or partially opened fibers aresubjected to only mild mechanical impact or impingement contact with thewall and fin surfaces of the cleaning chamber and with the blades 2l ofthe' impeller fans. Provision is made to reduce as much as possiblesuchmechanical impact treatment of the fibers, and to substitutetherefore a of: limiting the velocity of the carrier gas stream at theperiphery of the vortex to a maximum of not to exceed 50 times gravitypull: developing transverse pulsations in the path of the bers byinterposing deector ns which extend not more than an inch or tworadially inwardly of the vortex periphery and which extend in adirection forming a small oblique angle with the direction of bermovement: and introducing blanketing air streams behind the deiiectorfins and in the direction of ber ow to partially .counterbalance thecentrifugal forces acting to push the open bers into contact with thewalls of the cleaning zone. Such factors cooperate to limit seriousattrition of fine open bers, without interfering too seriously with theforces applied to eect opening and cleaning of heavier unopened andcrude nbers. t

The present method of treating asbestos bers is a highly e'icient andsimple operation in which an upwardly rising gas vortex is utilized forsubstantially simultaneous ber opening and cleaning operations and forclassification and segregation of the resulting cleaned bers from heavynon-brous and light dust impurities, In the inner or axial zones of thevortex the material suspended in the vortex is classied by centrifugalforces, and all bers and impurities greater than-a desired size arereturned to the outer periphery of the vortex by a centrifugal force of10-50 times gravity. By continuing the upward and inward movement of thevortex through a zone which lies above the principal flberizing andcleaning zone, a highly efficient classification is secured in whichsubstantially all impurity particles below a predetermined size areentrained by the air which leaves the cleaning chamber through thecentral air exit port. The inverted cone frustrum linings which aremounted in the berizing and cleaning sections of each treating chamberoperate somewhat as reverse venturis on the upwardly and inwardlyspiralllng air vortex, by reducing the velocities of the inward androtational components of the air flow in the upper zones of the chamber,thus concentrating the ilber opening and cleaning section of theapparatus primarily within that section of the apparatus which isbounded by the cones, while promoting final classification andseparation of light dust impurities by entrainment, in the upper zone ofthe cleaning chamber.

Operations which take place in the last cleaning chamber 20 of a seriesare primarily those of classiiication and segregation, although thischamber is also designed to carry out some opening and cleaningtreatment of crude iibers. In

this chamber the general flow of bers from the bestos ber opening andcleaning method of the present invention, the following results wereobtained by treating a measured charge of unclean crude asbestos bers inapparatus of the dimensions heretofore given, assembled in the mannerportrayed in Fig. 1. The crude bers as charged to the apparatuscontained a usable ber content of 53% by weight, and said crude bersclassied as to size with an average length of approxi'- mately 62microns and an average diameterof approximately 58 microns. The crudebers were delivered to the apparatus at a feed rate of 600 lbs. perhour, and the treatment was carried out supplying air to each cleaningunit at the rate of 400-450 cu. ft./minute. The yield of stillincompletely cleaned open bers which was obtained in ber separator 36was 63% by weight of the crude ber charged to the unit, and such cleanbers classied to an average length of approximately 350v microns and anaverage diameter of approximately 18 microns. The large apparentincrease inA average ber length results from removal of a highproportion of very short bers or nes by the classication process. Theheavy gangue which was discharged from the base of the last cleaningchamber 20 analyzed 17.4%

ofusab'le crudy ber, and the lightdust which was accumulated in dustseparators!! analyzed 28% of very ne short bers of a grade suitable foruse in the manufacture of asbestos paper,

asbestos-cement shingles and plastics. By this opening and cleaningmethod as applied to crude asbestos it is possible to recover a majorportion of the brous content within very narrow size classificationlimits and to separate undesired short bers in a manner which makes themreadily available for other uses as llers and the like. Since manyvariations may be made from the illustrative details given. withoutdeparting from the scope ofthe invention, it is intended that theinvention should be limited only by the terms of the claims.

What I claim is:

1. The method of treating asbestos bers to separate coarse and neimpurities adhering thereto comprising, introducing the bers to becleaned into an upwardly spiralling vortexv of a gaseous uid,maintaining a high volume ratio of gas to ber to provide a, thinsuspension of bers, maintaining a high ratio of rotational movement inrelation to gravitational movement4 of bers whereby to develop a path ofber travel of such length that the bers are combed into longitudinalalignment with the rotational direction of their movement, periodicallydeecting the rotational gas ow inwardly at spaced points adjacent theperiphery of the vortex,thereby developing components of lgas movementwhich are transverse to the direction of ber rotation and causing exingand bending of the bers whereby to loosen and scour impurities from theber surfaces, and nally separating the clean bers from heavy granularimpurities and from light dust impurities by removing the bersperipherally from the vortex while entraining the dust in the upwardlymoving gas and removing heavy impurities by gravitational settling.

2. The method of opening and cleaning crude asbestos. bers whichcomprises, suspending the bers in an air vortex while rotating the airadjacent the periphery of the vvortex at a velocity suicient to comb thebers into longitudinal alignment with the rotational direction of theirmovement, periodically developing air movement adjacent the periphery ofthe vortex in a direction transversely to the direction of ber move 4.The method of treating crude asbestos bers to open'vthe bersl andseparate impurities comprising, suspending the crudy bers in an upwardlymoving airV vortex while rotating the air adjacent the periphery ofthevortex at a velocity suicient to comb the bers into longitudinalalignment with the rotational direction of their movement, deecting theow of airat intervals adjacent the periphery of the vortex to eectperiodic air movement transversely to the direction of ber. movementwhereby to lilex and bend the bers, thereby splitting the bers andliberating impurities, and adjusting the rotational and verticalcomponents of the air ow to eilect separation of ne impurities byentrainment in the upwardly movingair and separation of heavy impuritiesby gravitational settling, while removing clean opened 'bers from theperiphery of the vortex. c v

5. The method of treating crude asbestos vbers -to open the bers andseparate impurities comprising. suspending the crudy .bers in anupwardly moving air vortex, rotating'the air adjacent the periphery ofthe vortex at a velocity sufllcient to comb the' bers into longitudinalalignment with the rotational direction of their movement, deecting'theow of air -at intervals adjacent the periphery of the vortex -to effectperiodic air movement transversely to the direction of ber movementwhereby to ex and bend the bers; thereby splitting the bers andliberating heavy impurities, vertical components moval ofbers byadjusting the rotational and of the air ow to effect resuspension in theupwardly moving vortex, and removing heavy impurities from the peripheryof the vortex by centrifugal action while simultaneously introducingclean air laterally to the vortex at the points of heavy imv purityremoval at a rate suicient to prevent removal of clean ber bycentrifugal action.

6. The method of simultaneously opening and cleaning crude asbestos berswhilegavoiding substantial degradation thereof which comprises,continuously feeding bers to be cleaned at a measured rate into anupwardly spiralling vortex of a gaseous uid, maintaining a high volumeratio of gas toiber to provide a thin suspension l high ratio ofrotational ii tational gas ow inwardly et spaced points adja= cent theperiphery of the vortex, thereby developing components of gas movementwhich are transverse to the rotational direction of ber movement andcausing flexing and bending of the bers whereby to open the bers andloosen and scour impurities from the ber surfaces, and nally separatingopened and cleaned bers from heavy crudy bers and granular impurities byremoving the clean bers peripherally and selectively from the vortex.

'7. The method of treating asbestos bers as dened in claim 6, includingthe step of removing ber in suspension outwardly from the periphery ofsaid gas vortex by causing `a reversal in the directional flow of theber by' establishing a pressure drop between the path of ber' removaland the periphery of the vortex, and adjusting the pressure differentialthus established to avoid contamination of the' removed bers by gascarrying nonbrous impurities in suspension.

8. The method of opening and cleaning asbestos bers which comprises,forming and maintaining an upwardly s piralling vortex of air,introducing asbestos bers to be treated into said air vortex,maintaining a high volume ratio of air to ber to provide a thinsuspension of bers, adjusting the. rotational and upward ow coniponentsof the air body toL maintain a high ratio of rotational movement inrelation to gravitational downward movement of the bers, whereby todevelop a path of ber travel of such length that the bers are combedinto longitudinal alignment with the rotational direction of theirmovement, deecting the air ow at intervals adjacent the periphery of thevortex whereby to develop components of air movement which aretransverseto the direction of rotation, thereby causing exing andbending of the bers and loosening and scouring of rock and dustimpurities from the ber surfaces, and simultaneously opening the berswhile avoiding substantial degradation thereof by said exing and bendingtreatment.

9. The method of treating crude asbestos bers -to open the bers and toseparate rock gangue and dust adhering thereto comprising, suspendingthe crudy bers in an upwardly moving 'air vortex while rotating the airadjacent the periphery of the vortex at a velocity suicient to com-b thebers into longitudinal alignment with the rotational direction of theirmovement, deiiecting the ow of air at intervals adjacent the peripheryof the vortex to effect periodic air movement transversely to thedirection of ber movement whereby to ex and bend the bers,

,thereby splitting the bers and liberating rock gangue and dusttherefrom, and adjusting the rotational and vertical components of theair flow to effect separation of granular gangue particles by gravitysettling and of ne dust particles by suspension in the upwardly movingvortex.

10. The method of opening and cleaning crude asbestos bers whichcomprises, establishing and maintaining two upwardly spiraling vortexesof air, introducing asbestos bers to be treated into the upper portionof the rst air vortex, discharging partially cleaned bers tangentiallyfrom the bottom of the rst vortex into the upper portion of the secondvortex, maintaining in each vortex a high volume ratio of air to ber toprovide a relation to gravitational downward movement of bers whereby todevelop a path of ber travel of escasas such length that the fibers areoriented into gitudinal alignment with the rotational dir. of theirmovement, deecting the air ow at *ntervals adjacent the periphery cieach vor tex whereby to develop components of air movement which aretransverse to the direction of rotation, thereby causing exing andbending oi the bers and opening and scouring of impurities from the bersurfaces while avoiding substantial degradation thereof; separatinglight dust impurities from the bers in the rst vortex by entrainmentremoval of said dust in air discharged axially from the top of thevortex, and separating cleaned bers from heavy granular impurities andunopened bers by entrainment of opened and cleaned bers in airdischarged tangentially from the upper portion of the second vortex.

ll. Apparatus adapted for the opening and cleaning of asbestos berscomprising, two upright cylindrical chambers, means in each chamber fordeveloping and maintaining therein an vupwardly rising gas vortex, aninlet port in each chamber for introducing ber to be treated into theupper portion of the vortex, an exit port in each chamber for removingcleaned bers tangentially from said chamber, a conduit connecting theexit port of one chamber in series with the ber inlet port of the secondchamber so that ber discharged from the tangential outlet of the firstchamber is introduced through the ber inlet port` of the next chamber,and a ber opening and cleaning zone in each chamber, said zone beinglargely conned within an inner wall lining extending throughout asubstantial proportion of the chamber length comprising spaced reentrantns each projecting a short radial distance inwardly into the path of thevortex.

12. Asbestos ber opening and cleaning apparatus comprising an uprightcylindrical chamber, an vair inletr port located centrally at the baseof the! chamber, a tangential air exit port located in the upperperipheral portion of said chamber, means for establishing andmaintaining an upwardly rising air vortex within the chamber, aninverted frusto-conical baiiie projecting inwardly and downwardly fromthe upper portion of the chamber wall above and in front of the air exitport, spaced peripheral slots in said baille, deflecting ns projectinginwardly in front of each slot in the direction of vortex ow, and meansin the lower portion of the chamber designed to segregate and separateheavy and coarse impurities from clean ne bers suspended in the upwardlyrising vortex, said means including scalping ns projecting inwardly ashort distance at spaced intervals about the periphery of the vortex ina direction opposed to and forming an oblique angle with the directionof vortex ow, and slots positioned immediately in front of each n in thedirection of gas ow, the forward edge of each fin forming a means fortrapping and deecting through said slots heavy coarse impurities broughtin contact therewith under the centrifugal force of said vortex.

13. Asbestos ber cleaning and separating apparatus comprising, anupright cylindrical drum, gas intake and discharge ports locatedrespectively at the base and top of the drum, a ber charging portopening into 'the top of the drum, a tangential ber discharge port atthe base of the drum, means for establishing and maintaining an upwardlyrising gas vortex within the drum, an inverted frusto-conical innerlining for the lower portion of the drum having its upper rim engagingand attached to the drum walls, said 13 lining being spaced from thedrum wall over a major portion of its height, slots at spaced intervalsaround the periphery of said inner lining, and deflector fins extendinginwardly a short distance at an oblique angle in front of each slot inthe direction of vortex flow.

14. In cyclone opening and cleaning apparatus for unclean asbestos, thecombination of an upright cylindrical drum, means for establishing andmaintaining within said drum an upwardly rising air vortex, means forintroducing fibers to be cleaned into the upper portion of said vortex,an inverted frusta-conical lining mounted in the drum with its top rimengaging and attached to the drum walls, said lining being spaced fromthe drum walls over major portions offits height slots at spacedintervals around the periphery of said lining, a tangential air outletported out of the drum behind thellining, delecting ns in front of eachslot in the lining in the direction of k vortex now, and scalping nsbehind each slot in the lining in the direction of vortex flow.

15. Asbestos fiber cleaning and separating apparatus comprising anupright cylindrical drum, gas intake and discharge ports locatedrespectively adjacent the base and top of the drum, a ber charging portopening into lthe top of theV drum, a tangential ber discharge port atthe base of the drum, a heavy impurity discharge port located centrallyat the base of the drum, an inverted frusta-conical inner lining for thelower portion of the drum,

each slot in the direction of vortex flow, and sets of fan bladesmounted labove and below the frusta-conical lining within the drum andarranged to establish and maintain an upwardly rising vortex within thedrum.

16. In cyclone opening and cleaning apparatus for crude bers, twoupright cylindrical drums, means for establishing and maintainingwithineach drum an upwardly rising air vortex, charging ports for introducingbers to be cleaned into the upper portion of each drum, a tangential vthe second drum with the -lll ber discharge port at :the a conduitconnecting the base of the first drum, fiber charging port of berdischarge port of the iirst drum, an axial air outlet port at the top ofthe first drum, inverted frusto-conical lining members mounted in a,lower portion of each drum with their top rims engaging and attached tothe drum walls, another inverted frusto-conical lining membermounted inthe upper portion of the second drum, said lining members being spacedfrom the drum and positioned in the path of the of their heights, atangential air and fiber outlet port for the second drum behind Ytheupper lining member, slots at spaced intervals around the periphery ofeach lining member, deecting fins projecting inwardly in front of eachslot in the direction of vortex ow in the upper lining of the seconddrum and in the lower lining of the rst drum, and scalping finsprojectinginwardly behind each slot in the lower lining of the seconddrum.

FRANK J. KOEHNE.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 505,977 Fletcher Oct. 3, 18931,023,750 Morscher Apr. 16, 1912 1,484,208 Davis Feb. 19, 1924 1,505,742Stebbins Aug. 19, 1924 1,509,915 Stebbins Sept. 30, 1924 1,595,257Stebbins Aug. 10, 1926 1,595,258 Stebbins Aug. 10, 1926 1,675,941Lindsay July 3, 1928 1,978,802 Lissman Oct. 30, l1934 2,026,833Holland-Letz Jan. 7, 1936 2,032,827 Andrews Mar. 3, 1936 2,039,692 VanTongeren May 5, 1936 2,125,086 Rourke July 26, 1938 2,128,166 SchmidtAug. 23, 1938 2,128,194 Sheldon Aug. 23, 1938 2,152,114 Van Tongeren\Mar. 28, 1939 2,214,658 Browning Sept. 10, 1940 2,280,903 Ellison Apr.28, 1942 upwardly rising vortex over major portions' Certificate ofCorrection Patent No. 2,460,938. February 8, 1949.

FRANK J. KOEI-IN E It is hereby certified that errors appear in theprinted specification of the above numbered patent requiring correctionas follows:

Column 1, line 16, for the word windowing read willowing; column 6, line51,

i for periphery read peripheral;

and that the said Letters Patent should be read With these correctionstherein that the same may conform to the record of the case in thePatent Oce.

Signed and sealed this 5th day of July, A. D. 1949.

[SEAL] THOMAS F. MURPHY,

Assistant Uommz'ssz'fmer of Patents.

